Automatic swimming pool cleaning apparatuses have become very popular for the cleaning of swimming pools. A variety of different designs of automatic pool cleaners are known to the applicant.
A common feature of most automatic pool cleaners is that they are propelled over the surface to be cleaned when water is induced to flow through a cleaning head of the apparatus by the suction of conventional swimming pool circulation equipment. The circulation is repeatedly interrupted at least to a substantial degree, by a valve or other means in the cleaning head, causing a pulsating flow as a result of which a pulsating force is generated which moves the apparatus in small steps in a random pattern over the floor and walls of the swimming pool. This allows the surfaces to be cleaned by water flowing through the swimming pool cleaning apparatus via a suction hose to the circulation equipment which usually comprises a filter such as a sand filter which filters out any dirt picked up by the cleaning apparatus.
Automatic swimming pool cleaning apparatuses of the aforementioned type are generally also equipped with a substantially flat circular cleaning disc made of a flexible material which engages with and holds the cleaning head in contact with the surface to be cleaned. Such conventional pool cleaning apparatuses are described for example in U.S. Pat. Nos. 3,803,658 to Raubenheimer, 4,023,227 to Chauvier, 4,133,068 to Hofman, 4,642,833 to Stoltz et al and 4,769,867 to Stoltz.
It is a common feature of all the aforementioned swimming pool cleaning apparatuses that they move around the pool in a random fashion. The direction of travel is influenced by the position of the suction hose, the shape of the swimming pool and forces acting on the suction hose and/or cleaning apparatus, such as return water jets, wind, wave action, gravity, flotation, hose stiffness, etc. These forces acting on the hose and/or the swimming pool cleaning apparatus could have the result that not all of the internal surfaces of the swimming pool are traversed at the same frequency, with the result being that some areas may not be cleaned as efficiently or as frequently as operating conditions in the pool may demand. Worse yet, some areas may not be cleaned at all.
In an effort to improve the cleaning pattern, a variety of devices have been fitted to conventional swimming pool cleaning apparatuses. They generally comprise a buoyancy member in combination with a weight, both of which improve the random pattern of movement. They cannot, however, effectively steer the swimming pool cleaning device on the floor or wall surfaces of the swimming pool, with the result that long cycle times are required to clean the pool completely. Under adverse conditions as aforesaid, they sometimes still fail to reach certain areas of the pool, such as in the region of the return flow jet.